Ash arrester



May 26, 1942. R. w. COWARD ASH ARRESTER Filed Sept. 30, 1939 All-LI a lll.lu

p y-"lulu" INVENTGR moocooo,

RICH/7RD (cow/9RD Patented May 26, 1942 UNITED STATES PATENT OFFICE ASHARRESTER Richard W. Coward, Birmingham, Ala. Application September 30,1939, Serial No. 297,300

4 Claims.

This invention relates to ash or cinder col lectors for use inassociation with solid fuel fired furnaces, and has for an object theprovision of apparatus of the character designated which shall be simpleand economical of design, involve no moving parts, and which shall beeffective to collect the major portion of such fine ash and cinders aswould otherwise be carried by the draft out of the smoke stack.

A still further object of my invention is to provide means in the smokestack of a furnace to impart a helical movement to the gases escaping upthe stack together with cinders and fine ash, causing the cinders andash to move to the perimeter of said path, and to provide means in thewalls of said stack to catch said cinders and ash.

In its broader aspects my invention is adapted to separate solidscarried in suspension in any gas current, and to that end it providesmeans for imparting a helical movement to such gases and tangentialopenings in the surrounding casing out of which solid particles move dueto centrifugal force.

It has heretofore been proposed to catch cinders and fine ash as theypass up a chimney by placing a helicoid in the path in the chimney toimpart a helical path of movement to the gases as they pass up thechimney and providing an annular chamber with openings in the innerwalls and vanes which were expected to direct the cinders and ash intothe annular chamber. So far'as I am aware, none of these proposals havegone into commercial use. In my investigation of the prcblemI have foundthat when the gases of combustion are subjected to a helical path ofmovement, the cinders and fine ash borne thereby'do not move altogetherin curved paths with the gases, but travel more in straight lines,bouncing around inside the cylindrical wall in short chords; the heavierthe particle, the longer the chord. At the same time, any obstruction tothe gas flow creates eddies which divert the cinders and fine ash fromtheir more or less regular paths of travel.

I have accordingly devised a cinder and ash collector of the generalcharacter above described, which comprises a helicoid disposed withinthe chimney in the path of the gases of combustion and which issurrounded by an annular chamber having slits in the walls through whichthe cinders and fine ash may pass. Except for the slits the walls of theannular chamber are smooth so that no eddies are produced in the path ofthe gases. vanes formed by cutting the slits in the wall of the chamberare turned inwardly of the chamber and aid in admitting the ash into theannular chamber. In addition, I may provide a jet acting to produce apressure within the annular chamber below that in the stack which thusaids in inducing a fiow of the gases with the fine ash and cinders instraight lines through the slits into the annular chamber.

Apparatus embodying features of my invention is illustrated in theaccompanying drawing forming a part of this application, in which Fig. lis a vertical sectional view of a chimney having my improved cinder andash arrester disposed therein;

Fig. 2 is a fragmentary sectional view taken along the line II-II ofFig. 1;

Fig. 3 is a development view of the apparatus showing the principalparts in one plane; and

Fig. 4 is a diagrammatic view showing the application of the apparatusto a boiler furnace.

Referring to the drawing, particularly Figs 1 to 3, I show a chimney H1in which is disposed a helicoid having double flights II and I2surrounding a central stem l3. Surrounding the helicoid and joinedthereto, as by welding, is a wall I4 in the form of a vertical casingwhich is supported from the outer wall of the chimney at top and bottomby means of angles 16 and I! so as to form an annular space I8 betweenthe inner and outer walls. By reference to Figs. 1 and 2 of the drawing,it will be seen that the helicoid flights are illustrated as extending270", or a sufficient distance to insure that no particles can escape upthe chimney while travelling in straight lines, but must move aroundinside the chimney a sufiicient distance to have imparted thereto ahelical movement. The chamber 18 extends above the helicoid flights aconsiderable distance; in the example shown the helicoid having a heightequal to of the total height of the apparatus and the chamber above thehelicoid of the total height; the total length of the apparatus as shownamounting to from 3.2 to 3.6 times the inner diameter of the chimney.While it is understood I-do not desire to be limited to the exactproportions shown, these proportions have been found admirably suitedfor the purposes set forth.

The sum of the areas between the two helicoid flights measured normal tothe surfaces thereof should be substantially equal to the crosssectional area of the apparatus at the base of the helicoid flights sothat the speed of the gases is not materially accelerated or retarded.Otherwise flights be employed to impart a helical path to the gases andto deflect the solid material, for the reason that a single flight mustnecessarily extend more than 360 around the apparatus to prevent shortcircuiting by the gases and solid material, and thus makes the apparatusof impractical length. While I have illustratedadouble flight, it willbe apparent to thoseskilled in the art that any number of flights, morethan a single flight, may be employed, and that the greater the numberthe more truly helical the flow of the gases will be when they enter thesection above the flights.

There. are formed in the wall 14, principally above the. upper end ofithehelicoid, a series of slots I9, each of which is preferably made upof a'series of relatively short aligned slots with bridges 2| betweenthe continuations of each such slot whereby to prevent warping. Theslots are arranged around the wall I 4 in series forming helical paths,particularly as seen in Fig. 3, above the helicoid, and in the projectedhelicoidal paths of the gases passing up through the ch'imney. I havefound feature important in that continuous slots of uniform length andstarting at substantially the same level around thechimney permitthe'cinders and fine ash to enter at the bottom and remain in'suspensionuntil-they pass out at the tops of the slots and require some meanswithin the annular chamber to deflect them downwardly. Such a deflectoris shown at 2!! in Fig. 2. When arranged in helicoidal series in.theproje'cted paths of the gases, the fine ash and cinders' areseparatedfrom thegases and deposited in the annular chamber. a

As shown in Fig. 2, the slots l9; are formed by slitting the metal andturning 'the'lips "22 from the upstream sides of the 'slotsinwardly ofthe space i 8 between the walls of the annular chamber tangential to theinner wall and extending to a line substantially even with thedownstream edges of the slots. The lips 22 thus serve to guide the ashand cinders'along straight lines into the annular space and to separatethe fine ash. and cin'der's'from the gases in the annular chamber. Also,there being no lips or vanes projecting inwardly of the chimney in thepath of the gases, there are no troublesome eddies formed which woulddivert the light ash and cinders away from the slotsl9.

It will also beseen, by reference to Figs. 1 and 3, that the slots H!are provided in the wall It principally abovethe upper end of thehelicoid and that the annular chamber extends a sub stantial distanceabove the upper end of the helicoid, bein gin extentv greater than thetotal length er the helicoid; I thus provide for an opportunity for themajor portion of the ash and cinders to enter the annular chamber and becollected. 7

,7 -'I'he ash and cinders collected in the annular chamber fall bygravity to the lower portion thereof anddrain out through a plurality ofdownwardly extending passages 23 at the bottom thereof and arefin'ally'discharged through a conduit 24 to which the passages 23 arejoined.

As shown in Fig. 4, where my improved device is associated with a boilerfurnace 26, I may provide an ejector 21 which joins, through a conduit28, with the conduit 24 to discharge the ash and cinders therefrom, andalso acts to maintain a pressure within the chamber [8 below that in thestack to induce the cinders and the ash to enter through the slots Hi.If preferred, the said cinders and ash may be discharged through aconduit 29 into the fire box of the furnace. It will also be obviousthat they may be disposed of in many other ways known to the art.

From the foregoing it will be apparent that I have devised an improvedash arrester which is simple of construction and operation, has nomoving parts; and which effectively arrests cinders and fine ash passingup a chimney with the gases of. combustion. 7

While I have shown my invention in but one form, it will be obvious tothose skilled in the art that it is notso limited, but. is susceptibleof various changes and" modifications, without departing from the spiritthereof, and I desire, therefore, that only: such limitations shall bepla'cedfthereupon as are specifically set forth in the appended claims.

WhatI claim is: .J

1. A separator comprising-a casing through which gasesbearing'solidspas's', .afdouble heli-L coid disposedwithin the casing toimpart a helical movement to the gases, wallet-defining an annularchamber fltting'snugly about the hellicoid and extending therebeyond inthe direction of gas flow a distancegreater than the length ofthehelic'oid, the wall of the chamber beyond the helicoid being providedwith a plurality of axially extending rows of relatively short slitsdisposed in helical series'froma point in advance of the downstream endof the helicoid beyond in the projected path of the gases, thesaid wallbeing otherwise imperforate and uninterrupted and smooth except for saidslits, and flat vanes on the sides of the slits extending tangentiallyinward of the chamber toward the downstream side. g

2. A separator comprising a casing through which gases bearing solidspass, a double helicoid disposed within the casing to impart a helicalmovement to the gases, walls defining an annular chamber fitting snuglyabout the helicoid and extending therebeyond in the general'direction ofgas flow a 'distance greater than the length of the helicoid, thewall ofthe chamber beyond the helicoid being provided with a plurality ofaxially extending rows of relatively short slits disposed spirally inthe projected path of the gases, the said wall being otherwiseimperforat'eand uninterrupted andsmooth except for said slits, flatvanes on the sides of the slits extending tangentially inward of thechamber from the upstream sides of the slits to the downstream sidesthereof, and means to discharge trapped solids from and to maintain apressure within the annular chamber below that in the casing. V I r 3. Aseparator comprising a casing through which gases bearing solids pass,'a multiple flight helicoid disposed within' the casing to impartahelical movement to the gases, walls defining an annular chamberfittihgsnugly about the helicoid and extending therebeyond in thedirection of gas flow a distance greater than the length of thehelicoid, the wall of the chamber from a point slightly in advance ofthe end of the helicoid in the direction of gas flow and beyond thehelicoid being provided with a plurality of axially extending rows ofrelatively short slits disposed in helical series in the projected pathof the gases, the said wall being uninterrupted and smooth except forsaid slits, that portion of the wall surrounding the helicoid beingimperforate, and vanes on the upstream sides of the slits extendingtangentially inward of the chamber in the general direction of gas flowto the downstream sides of the slits.

4. A separator comprising a casing through which gases bearing solidspass, a multiple flight helicoid disposed within the casing to impart ahelical movement to the gases, walls defining an annular chamber fittingsnugly about the helicoid l5 and extending therebeyond in the directionof gas flow a distance greater than the length of the helicoid, the wallof the chamber near the downstream end of the helicoid and beyond thehelicoid being provided with a plurality of axially extending rows ofrelatively short slits disposed in helical series in the projected pathof the gases, the said wall being uninterrupted and smooth except forsaid slits, that portion of said wall surrounding the helicoid beingimperforate, vanes on the sides of the slits extending inwardly oi thechamber tangentially of the inner wall from the upstream to thedownstream sides of the slits, and means to discharge trapped solidsfrom the annular chamber.

RICHARD W. COWARD.

